Jiang Chen, an overworked corporate employee, is reborn as Chitong, an endangered Chinese sucker fish in the Yangtze River, and becomes bound to the Aquatic Emperor System. Cleverly using food supplied by Lao Wang, an avid fisherman, to obtain resources, he recruits Xuan Lao, a thousand-year-old turtle, as his strategist and gradually gathers groups of grass carp, whitebait, and other fish. With his intelligence and system abilities, he defeats Hei Sha, the tyrant black snakehead, and Shen Yuan, the king of the neighboring river. When illegal electrofishing threatens aquatic life, he leads his fish army in rescue operations and joins forces with blogger Lin Hao to expose the criminals, averting a human-led river-clearing crisis. Ultimately, he expands his aquatic empire through strategic decentralization, creates a viral internet-famous divine fish brand, establishes an aquatic wildlife conservation organization, and becomes the ruler of the waters, bringing humans and aquatic creatures into harmony.